| 摘要 |
PURPOSE:To drive a thermosensitive element at an optimum width pulse in accordance with battery consumption rate by detecting the battery consumption rate using a dummy load during non-printing operation and determining the drive pulse width of said element with an output of consumption rate detection. CONSTITUTION:A detection circuit 4 detects battery consumption rate and converts it to a pulse width. During a period of time corresponding to the battery voltage consumption rate, transistor Tr4 is kept in 'ON' position. If resistance R4 is higher enough than R2 and an electric current running through the resistance R4 is ignored, time T during which terminal p goes '1' and then terminal q goes '1' can be expressed by an equation where Vth represents a voltage between base emitters which is required for turning ON Tr4, Vf a battery voltage when Tr2 is in 'OFF' position and Vn a battery voltage when Tr2 is in 'ON' position. The battery consumption rate can be determined by measuring a pulse width generated from the terminal q with a microcomputer. Based on the value thus obtained, the width of a drive pulse for a thermal element 3 is set. Then the thermal element 3 is driven at a pulse width corresponding to a battery voltage, thus performing the printing. |
